1. Field of the Invention
The present invention relates to a printing apparatus such as a printer or a photocopying machine, and more particularly, to a printing apparatus having plural printing paper loading devices to store printing papers, and a method of setting IDs of the plural printing paper loading devices.
2. Description of the Related Art
A printing apparatus such as a printer or a photocopying machine to output letters and pictures on printing papers has a printing paper loading device to store papers used in printing. When the printing apparatus performs the printing, the printing papers stored in the printing paper loading device are taken out by a printing paper delivery device, such as a roller, and are transmitted to a printing unit. Known designs include a printing apparatus having plural printing paper loading devices. Since various types of printing papers can be loaded into the plural printing paper loading devices, a user can select the proper size and type of paper for the particular print job.
The printing apparatus having the plural printing paper loading devices has a selection means for the user to select a desired printing paper loading device from among the numerous printing paper loading devices. For example, when the user selects one of the printing paper loading devices by using a manipulation button provided on a manipulation panel of the printing apparatus, a printing paper loaded in the selected printing paper loading device is used during the printing operation.
However, in the printing apparatus having the plural printing paper loading devices, IDs (Identification Codes) for each of the printing paper loading devices should be set in advance before the user inputs a selection command with respect to the printing paper loading devices. The printing paper loading devices are consecutively given numbers, starting at 1. For example, 1 is given to a printing paper loading device placed at the highest position, and 2 is given to a next printing paper loading device. The IDs can be set while the printing paper loading devices are being manufactured, or can be set afterwards for the user's convenience when the printing paper loading devices are additionally installed in accordance with the user's needs.
FIG. 1 is a block diagram schematically showing the conventional printing apparatus having conventional plural printing paper loading devices. The printing apparatus in FIG. 1 has three printing paper loading devices. The printing apparatus includes a main controller 10, first through third printing paper loading devices 20A–20C, and first through third cassette controllers 22, 24 and 26 respectively disposed in the printing paper loading devices 20A–20C.
The main controller 10 controls overall operations related to printing, such as interfacing printing data with a host connected with the printing apparatus, data processing, controlling various motors, and controlling various sensors. The first through third cassette controllers 22, 24 and 26 are independently connected with the main controller 10 through three data buses 15a, 15b and 15c. The controllers 22, 24 and 26 control the operation of a printing paper delivery motor (not shown) and a printing paper delivery sensor (not shown) in each of the printing paper loading devices 20A–20C, in accordance with a command transmitted from the main controller 10.
In the above printing apparatus, the data buses 15a, 15b and 15c are allocated to each of the printing paper loading devices 20A–20C. Accordingly, the main controller 10 can set the IDs with respect to each of the first through third printing paper loading devices 20A–20C.
FIG. 2 is a view showing another example of a conventional printing apparatus having the conventional printing paper loading devices. As in FIG. 1, the printing apparatus has a main controller 30, first through third printing paper loading devices 40, and first through third cassette controllers 42, 44 and 46, respectively disposed in each of the printing paper loading devices 40. Moreover, the cassette controllers 42, 44 and 46 are connected with the main controller 30 through a common data bus 35. Each of the cassette controllers 42, 44 and 46 has ID set-up switches 41, 43 and 45 to manually set an ID.
In the above printing apparatus, as the main controller 30 and each of the cassette controllers 42, 44 and 46 transmit data through the common data bus 35, the main controller 30 can recognize the IDs of the printing paper loading devices 40 according to a set-up state of the ID set-up switches 41, 43 and 45. The main controller 30 also transmits the data to the proper one of the printing paper loading devices 40 to be controlled based on a recognized ID.
In the case of FIG. 1, when the main controller 10 and each of the cassette controllers 22, 24 and 26 respectively have the independent data buses 15a, 15b and 15c, the cost of manufacturing the printing apparatus increases as the number of the data buses 15a, 15b and 15c increases. In addition, when an additional printing paper loading device is installed afterwards, an additional data bus must be provided.
In the case of FIG. 2, when the separate ID set-up switches 41, 43 and 45 are installed in the printing paper loading devices 40, the user has to manually set the IDs for the respective printing paper loading devices 40. Additionally, when the user mistakenly sets a same ID for different ones of the printing paper loading devices 40, the command of the main controller 30 is transmitted to plural ones of the printing paper loading devices 40, which may cause serious damage to the printing apparatus.